{"id":17874,"date":"2026-04-19T08:16:16","date_gmt":"2026-04-19T02:46:16","guid":{"rendered":"https:\/\/aluminiummagazine.com\/mag\/?p=17874"},"modified":"2026-04-19T08:16:18","modified_gmt":"2026-04-19T02:46:18","slug":"aluminium-tungstate-negative-thermal-expansion","status":"publish","type":"post","link":"https:\/\/aluminiummagazine.com\/mag\/aluminium\/compounds\/aluminium-tungstate-negative-thermal-expansion.html","title":{"rendered":"Aluminum Tungstate (Al\u2082(WO\u2084)\u2083): The Complete Guide"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Aluminum tungstate is an inorganic mixed oxide with the formula Al\u2082(WO\u2084)\u2083. It appears as a dense white powder, is insoluble in water, and is valued almost exclusively in materials science research for a rare property: <strong>isotropic negative thermal expansion (NTE)<\/strong> \u2013 it shrinks uniformly in all directions when heated, opposite to most materials.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">1. <strong>Basic Identification<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Chemical Formula:<\/strong> Al\u2082(WO\u2084)\u2083<\/li>\n\n\n\n<li><strong>Alternative Names:<\/strong> Aluminium(III) tungstate<\/li>\n\n\n\n<li><strong>Molecular Weight:<\/strong> 797.4 g\/mol<\/li>\n\n\n\n<li><strong>CAS Number:<\/strong> Not assigned (research compound)<\/li>\n\n\n\n<li><strong>Appearance:<\/strong> Dense, white micro\u2011crystalline powder<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">2. <strong>Physical Properties<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Property<\/th><th class=\"has-text-align-center\" data-align=\"center\">Aluminum Tungstate<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Melting Point<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">~1100\u202f\u00b0C (decomposes before true melting)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Density<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">~4.6 g\/cm\u00b3<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Crystal Structure<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Orthorhombic (corner\u2011sharing AlO\u2084 and WO\u2084 tetrahedra)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Thermal Expansion<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Isotropic negative (shrinks uniformly from ~0\u00b0C to 1000\u00b0C)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Solubility<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Insoluble in water and organic solvents<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">The material is dense, inert, and non\u2011hygroscopic. It does not react with humidity or ambient oxygen.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">3. <strong>Chemical Behavior &amp; Synthesis<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">3.1 Isotropic Negative Thermal Expansion (NTE)<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">In most solids, heating increases atomic vibrations, pushing atoms apart (positive expansion). In aluminum tungstate, the oxygen atoms act as hinges between rigid AlO\u2084 and WO\u2084 tetrahedra. As temperature rises, transverse vibrations of these bridging oxygen atoms pull the metal centers closer together \u2013 causing the entire lattice to contract. Uniquely, this contraction occurs equally in all three dimensions (isotropic), avoiding internal cracking.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">3.2 Synthesis<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Prepared by solid\u2011state reaction:<\/p>\n\n\n\n<p class=\"has-large-font-size wp-block-paragraph\"><strong>Al\u2082O\u2083 + 3 WO\u2083 + Heat \u2192 Al\u2082(WO\u2084)\u2083<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">High\u2011purity aluminum oxide and yellow tungsten trioxide are finely ground, then calcined at 800\u20131000\u202f\u00b0C for several hours. The product is a dense, crystalline powder.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">4. <strong>Research &amp; Potential Applications<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">4.1 Zero\u2011Expansion Composites (Aerospace &amp; Optics)<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Spacecraft and orbital telescopes experience extreme temperature swings (\u2212150\u00b0C to +150\u00b0C). Normal materials expand and contract, causing misalignment. By mixing aluminum tungstate (which shrinks when heated) with a conventional material that expands, researchers can create composites with near\u2011zero net thermal expansion. This is studied for precision optical benches, satellite booms, and laser housings.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><em>Note: Commercial use is limited due to hydration sensitivity and decomposition above ~1100\u00b0C. Most work remains at the research stage.<\/em><\/p>\n<\/blockquote>\n\n\n\n<h3 class=\"wp-block-heading\">4.2 Trivalent Ion Conductor Research<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Conventional batteries rely on single\u2011charge ions (Li\u207a, Na\u207a). Aluminum has a +3 charge, potentially offering higher energy density. Researchers study aluminum tungstate as a solid electrolyte for trivalent ion conduction, but this is highly experimental and far from practical application.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">5. <strong>Safety &amp; Hazard Management<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Route of Exposure<\/th><th>Effect<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Inhalation<\/strong><\/td><td>Primary hazard. Prolonged dust exposure may cause lung irritation or fibrosis. Use P100 mask when handling bulk powder.<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Skin Contact<\/strong><\/td><td>Low hazard; insoluble and non\u2011corrosive.<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Eye Contact<\/strong><\/td><td>Mechanical irritant (like dust). Flush with water.<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Ingestion<\/strong><\/td><td>Low acute toxicity due to insolubility.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>PPE:<\/strong> P100 respirator, safety goggles, standard gloves.<br><strong>Storage:<\/strong> Sealed plastic drums; no special humidity control.<br><strong>Disposal:<\/strong> Do not discard in drains. Tungsten is valuable; send spent powder to metal reclamation.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">6. <strong>Environmental Impact<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Tungsten compounds have low solubility, so acute aquatic toxicity is limited. However, fine insoluble powders can physically affect filter\u2011feeding organisms. Recycling is preferred over landfill disposal.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">7. <strong>Comparison with Other Aluminium Oxides<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Compound<\/th><th class=\"has-text-align-center\" data-align=\"center\">Formula<\/th><th class=\"has-text-align-center\" data-align=\"center\">Thermal Expansion<\/th><th>Primary Application<\/th><\/tr><\/thead><tbody><tr><td><strong>Aluminium Tungstate<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Al\u2082(WO\u2084)\u2083<\/td><td class=\"has-text-align-center\" data-align=\"center\">Isotropic negative<\/td><td>Research \u2013 zero\u2011expansion composites<\/td><\/tr><tr><td><strong>Aluminium Titanate<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Al\u2082TiO\u2085<\/td><td class=\"has-text-align-center\" data-align=\"center\">Anisotropic negative (different by axis)<\/td><td>Diesel engine exhaust liners<\/td><\/tr><tr><td><strong>Aluminium Oxide<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Al\u2082O\u2083<\/td><td class=\"has-text-align-center\" data-align=\"center\">Positive<\/td><td>Ceramics, abrasives, insulation<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">8. <strong>Frequently Asked Questions<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: Is aluminum tungstate used in truck engines?<\/strong><br>A: No. Diesel engine components use aluminum titanate, which has anisotropic (direction\u2011dependent) negative expansion. Aluminum tungstate\u2019s isotropic shrinkage is more valuable for precision optics and space applications.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: What does \u201cisotropic\u201d mean?<\/strong><br>A: It means the material expands or contracts equally in all three dimensions. Aluminum titanate may shrink in one direction but expand in another, causing micro\u2011cracks. Aluminum tungstate shrinks uniformly, preserving structural integrity.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: Can I buy this for a hobby project?<\/strong><br>A: Unlikely. It is a research chemical, not a consumer product. It is expensive and available only from specialized chemical suppliers.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">9. <strong>Summary Data Sheet<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Property<\/th><th class=\"has-text-align-center\" data-align=\"center\">Value<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Chemical Name<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Aluminum Tungstate<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Formula<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Al\u2082(WO\u2084)\u2083<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Appearance<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">White, dense powder<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Melting Point<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">~1100\u202f\u00b0C (decomposes)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Defining Trait<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Isotropic negative thermal expansion<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Primary Utility<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Research \u2013 zero\u2011expansion composites for space\/optics<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Hazard Note<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Low toxicity; dust hazard only<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div><script>document.addEventListener(\"DOMContentLoaded\",function(){\n        if(window.innerWidth <= 768){\n            if (\"immediate\" === \"delay\") {\n                setTimeout(function(){document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\")},0);\n            } else if (\"immediate\" === \"scroll\") {\n                window.addEventListener(\"scroll\",function(){\n                    let s=window.scrollY\/(document.body.scrollHeight-window.innerHeight);\n                    if(s>0.1){\n                        document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\");\n                    }\n                });\n            } else {\n                document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\");\n            }\n        } else {\n            document.querySelectorAll(\".pai-ad\").forEach(el=>el.remove());\n        }\n    });<\/script>","protected":false},"excerpt":{"rendered":"<p>Aluminum tungstate is an inorganic mixed oxide with the formula Al\u2082(WO\u2084)\u2083. It appears as a dense white powder, is insoluble in water, and is valued almost exclusively in materials science research for a rare property: isotropic negative thermal expansion (NTE) \u2013 it shrinks uniformly in all directions when heated, opposite to most materials. 1. Basic &#8230; <a title=\"Aluminum Tungstate (Al\u2082(WO\u2084)\u2083): The Complete Guide\" class=\"read-more\" href=\"https:\/\/aluminiummagazine.com\/mag\/aluminium\/compounds\/aluminium-tungstate-negative-thermal-expansion.html\" aria-label=\"Read more about Aluminum Tungstate (Al\u2082(WO\u2084)\u2083): The Complete Guide\">Read more<\/a><\/p>\n","protected":false},"author":12,"featured_media":17975,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4155],"tags":[4141,4142],"class_list":["post-17874","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-compounds","tag-aluminium-compounds","tag-aluminum-formula"],"_links":{"self":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts\/17874","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/comments?post=17874"}],"version-history":[{"count":0,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts\/17874\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/media\/17975"}],"wp:attachment":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/media?parent=17874"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/categories?post=17874"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/tags?post=17874"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}