Pressure effect on the phase transition temperature in (CH sub(3)) sub(2)NH sub(2)H sub(2)AsO sub(4)

The effect of hydrostatic pressure on the transition temperatures in (CH sub(3)) sub(2)NH sub(2)H sub(2)AsO sub(4) and (CH sub(3)) sub(2)N(H sub(0.5)D sub(0.5)) sub(2)(H sub(0.5)D sub(0.5)) sub(2)AsO sub(4) were investigated by dielectric measurements. A pressure-induced phase was newly observed for...

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Published in:Ferroelectrics 2000-01, Vol.237 (1), p.415/111-422/118
Main Authors: Hatori, Junko, Yamada, Takefumi, Shikanai, Fumihito, Komukae, Masaru, Osaka, Toshio
Format: Article
Language:English
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Summary:The effect of hydrostatic pressure on the transition temperatures in (CH sub(3)) sub(2)NH sub(2)H sub(2)AsO sub(4) and (CH sub(3)) sub(2)N(H sub(0.5)D sub(0.5)) sub(2)(H sub(0.5)D sub(0.5)) sub(2)AsO sub(4) were investigated by dielectric measurements. A pressure-induced phase was newly observed for (CH sub(3)) sub(2)NH sub(2)H sub(2)AsO sub(4) above 1.36 GPa at room temperature. The transition to the pressure-induced phase shows first order character. As pressure increases, the ferroelectric transition temperatures for both crystals monotonously decrease. Their pressure derivatives, dT sub(c)/d sub(p), were obtained to he - 49 plus or minus 1 K/GPa for (CH sub(3)) sub(2)NH sub(2)H sub(2)AsO sub(4) and - 52 plus or minus 1 K/GPa for (CH sub(3)) sub(2)N(H sub(0.5)D sub(0.5)) sub(2)(H sub(0.5)D sub(0.5)) sub(2) AsO sub(4). From the present experimental results. The lack of an appreciable isotope effect on dT sub(c)/dp was observed in (CH sub(3)) sub(2)NH sub(2)H sub(2)AsO sub(4).
ISSN:0015-0193