Physica B 329–333 (2003) 1658–1659 Design of 4GPa class hybrid high pressure cell for dilution refrigerator Yoshiya Uwatoko a, *, Masato Hedo a , Nobuyuki Kurita a , Masahito Koeda a , Melike Abliz a,b , Takehiko Matsumoto b a Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8581, Japan b National Institute for Material Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan Abstract We constructed the piston cylinder type hybrid high pressure cell using a home-made Ni–40Cr–3.5Al–0.005B alloy. It was designed in the hydrostatic pressure cell; 67 mm in length and 25 mm in outer diameter for using it with dilution refrigerator. We have succeeded in the resistivity measurement under hydrostatic pressure up to about 3:8 GPa at temperatures down to T ¼ 33 mK: r 2003 Elsevier Science B.V. All rights reserved. Keywords: Hybrid high pressure cell; Ni–Cr–Al alloy 1. Introduction In the strong correlated materials, physical property studies under high pressure become more important. These physical properties are very sensitive to hydrostatic nature. Among them, many piston cylinder type high pressure apparatus with large sample space have been designed by using Cu–Be alloy for clarifying the physical properties (see for example Ref. [1]). However the pressure limits should be only up to 2 GPa due to the limit of the tensile strength of Cu–Be alloy. The strong non-magnetic materials Ni–Cr–Al, which successfully generate the pressure over 3 GPa; have been introduced by Eremets [2]. In the present paper, the design of the cell is presented. For example, high pressure calibration and the electrical resistivity at dilution temperature of YbInCu 4 have been practically measured using the home made Ni–Cr–Al pressure cell. 2. Experimental details Ni–Cr–Al alloy rods were annealed at 12001Cfor1h; followed by water quenching. After machining, samples with disk shape were aged in the temperature range from 4001C to 9001C: For optimum mechanical properties, which were obtained at aging condition of 7001Cfor2h; the hardness became about 57 HRC. The results of hardness are almost the same as the previous one [3]. We have designed a conventional piston cylinder cell, which consists of a nonmagnetic WC and the Ni–Cr–Al inner cylinder inserted into the Cu–Be outer sleeve. A schematic drawing of the hydrostatic cell is shown in Fig. 1. The dimensions of cylinder are 63, 24 and 5 mm; in length, outer diameter and inner diameter, respec- tively. Basic idea of the cell is similar to the former designed hybrid cells [2]. The high pressure sample space was sealed by Teflon cell technique. As a pressure transmitting fluid a mixture of Fluorinert FC70 : FC77 ¼ 1:1 was used. 3. Calibration and resistivity measurements The pressure at room temperature and liquid helium temperature was determined from values of phase transitions P t ðFÞ for Bi, Tl and Te and the super- conducting transition temperature T C ðPÞ for Pb which have been well known as pressure dependence. The applied force dependent resistivity of Bi was measured at *Corresponding author. Tel.: +81-471-36-3330; fax: +81- 471-36-3331. E-mail address: uwatoko@issp.u-tokyo.ac.jp (Y. Uwatoko). 0921-4526/03/$-see front matter r 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0921-4526(02)02449-3