Pressure-temperature phase diagram of Ti2O3and physical properties in the golden Th2S3-type phase
Pressure-temperature phase diagram of Ti2O3and physical properties in the golden Th2S3-type phase
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DOI：
10.1103/physrevb.86.024106
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发表时间：
2012-07
影响因子：
3.7
通讯作者：
S. Ovsyannikov;Xiang Wu;A. Karkin;V. Shchennikov;G. Manthilake
中科院分区：
文献类型：
--
作者：
S. Ovsyannikov;Xiang Wu;A. Karkin;V. Shchennikov;G. Manthilake
本文研究了新近发现的金黄色倍半氧化钛(Ti2 O3)相S的合成压力和温度条件，以及其物理性能。在室温下的X射线衍射和拉曼高压相结合的研究中，我们发现在压力接近8 cha21 10 Gpa时有一个等结构转变的信号。这一发现与常压下发生的半导体-半金属等结构转变有关，该转变发生在400char21450K附近，在10 Gpa以上，在适当的加热条件下合成了金相。在原位高压高温(HP-HT)研究的基础上，结合在高压高温条件下合成的样品，首次建立了Ti2 O3的压力-温度相图。通过拉曼光谱、吸收光谱、反射光谱以及电阻率、霍尔效应、热电功率(Seebeck效应)和磁阻的测量对金多晶型样品进行了检测。此外，还进行了电子能带结构计算。确定了在常温下Ti2 O3的金色多晶型为半导体，其带隙为0.1 char2 1.2 eV，并测定了其典型的电子能带结构参数.
In this paper, the pressure and temperature conditions of the synthesis of a recently discovered golden Th${}_{2}$S${}_{3}$-type phase of titanium sesquioxide (Ti${}_{2}$O${}_{3}$) are studied, along with its physical properties. In combined x-ray diffraction and Raman high-pressure studies at room-temperature we found signatures of an isostructural transition at pressures near \ensuremath{\sim}8\char21{}10 GPa. This finding was addressed to the well-known isostructural semiconductor-semimetal transition that occurs at ambient pressure near 400\char21{}450 K. Above \ensuremath{\sim}10 GPa the golden phase was synthesized under appropriate heating. Based on both in-situ high-pressure high-temperature (HP-HT) studies in diamond anvil cells and ex-situ studies on samples synthesized at HP-HT conditions in multianvil cells, we constructed a pressure-temperature phase diagram of Ti${}_{2}$O${}_{3}$ for the first time. The samples of the golden polymorph were examined by Raman, absorption, and reflectance spectroscopy as well as by measurements of electrical resistivity, Hall effect, thermoelectric power (Seebeck effect), and magnetoresistance. In addition, electronic band-structure calculations were performed. We established that at ambient conditions the golden polymorph of Ti${}_{2}$O${}_{3}$ behaves as a semiconductor with an energy gap of \ensuremath{\sim}0.1\char21{}0.2 eV and determined its typical electronic band structure parameters.