137

ReviewJ. Jpn. Soc. Colour Mater., 96〔4〕，137–140（2023）

Preparation of the Negative Thermal Expansion Material Zr2SP2O12
and Related Materials
Toshihiro Isobe＊,†＊Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan†Corresponding Author, E-mail: isobe.t.ad@m.titech.ac.jp(Received November 30, 2022; Accepted December 25, 2022 )Abstract
Materials with a negative coefficient of thermal expansion (CTE) have been actively studied for compositing with materials with a high CTE
to control the CTE. Negative thermal expansion in Zr 2 SP 2 O 12 operates via two main unique mechanisms: phase transition ( 373–453 K)
and framework-type ( 303–373 K and 453–773 K). Zr 2 SP 2 O 12 is a promising material in this research field because of its relatively low
CTE over a wide temperature range. This study describes the mechanism of shrinkage of Zr 2 SP 2 O 12 and introduces control of the CTE byelemental substitution of the Zr sites.
Key-words: Ceramic, Crystal structure, Phase transition

1．Introduction
Thermal expansion is a fundamental property of a material.
The coefficient of thermal expansion (CTE) varies greatly
among materials, ranging from 10 to 30 ppm/K for metals,
50 to 200 ppm/K for plastics and resins, and 1 to 25 ppm/K
for ceramics and glass. Thermal expansion has long beenused for a wide range of purposes, from consumer toindustrial applications, such as thermometers and bimetals.
However, problems such as the elongation of railroad rails
and the destruction of tableware through thermal shock arealso widely known. In recent years, slight thermal expansion
has become a problem in areas such as optical devices andsemiconductor manufacturing, where precise positioning anddimensional control of components are required. In devices
that combine multiple materials, differences in the CTE ofeach material can lead to serious problems such as interface
delamination and wire breakage 1 ). Therefore, various nearzero thermal expansion materials and thermal expansion
control technologies have been studied. Invar alloys 2 ),glass 3 ), cordierite 4,5 ), etc., are widely known to exhibit near〔氏名〕 いそべ としひろ〔現職〕 東京工業大学物質理工学院 准教授，博士（工学）〔趣味〕 マラソン〔経歴〕 平成 13 年名古屋工業大学大学院博士課程前期修了。平成 15 年東京工業大学大学院博士課程後期修了。博士（工学）。平成 18 年産業
技術総合研究所産総研特別研究員。平成 20年東京工業大学特任助教，助教を経て，平成 31 年から現職。

【Figures and illustrations】Figures and illustrations published in black andwhite in the journal can be seen in color at our public website「J-STAGE」.
Please make use of it.

zero thermal expansion in a single phase and are applied inindustrial and consumer products 6 ). However, for materials
in which control of the CTE is difficult in the single phase,thermal expansion can be suppressed by compositing withfiller materials having a low CTE 7 ). In particular, materials
with a negative CTE, which shrink as the temperature
increases, can be used as filler materials because it isexpected that at low loadings, they can cancel the thermal
expansion of the structural material, thereby controlling only
the thermal expansion rate while maintaining the propertiesof the base material 8-14 ). Since the 2000s, many importantmaterials with negative CTE have been reported, and thefield has gained new momentum 15 ). Our research groupreported Zr 2 SP 2 O 12 as a new material. Zr 2 SP 2 O 12 hasa wide temperature range and a low CTE because ofmultiple shrinkage mechanisms. Therefore, it is considered
an industrially promising material. This study introduces
Zr 2 SP 2 O 12 and related materials.

2．Mechanism of negative thermal expansion
2.1 Phase transition-type mechanisms
The main mechanisms of negative CTE can be classified
into phase transitions and framework-type. The phasetransition-type is based on the volume change before
and after the phase transition ( Fig. 1 ) 14 ) . Generally,phase transitions and volume changes occur at specifictemperatures. However, the partial substitution of elements(or introduction of defects) into a material leads to a volumechange within the temperature range. The phase transitiontype pertains to a negative thermal expansion material that
undergoes this volume change.

－11－© 2023 Journal of the Japan Society of Colour Material