Original paper

A new radiative microfurnace for X-ray single-crystal diffractometry

Molin, Gianmario; Martignago, Fedora; Dal Negro, Alberto

Abstract

Microfurnaces available today for X-ray single-crystal investigation (radiative, gas-flame, gas-flow) are generally temperature-monitored by a thermocouple placed in a different site with respect to the crystal. The new F1 microfurnace aims at the following goals: fast crystal mounting; access to a large portion of reciprocal lattice; low absorption of direct beam; efficient in situ temperature measurement; fast power supply regulation; high temperature stability; controlled atmosphere. In the F1, the crystal is directly glued to a thermocouple with refractory cement. The heating body, fixed on the χ and radially shiftable along the Φ axis circle, hosts the Pt winding and connections of both gas flow and power supply, and is enclosed in a thin pyrolitic boron nitride (PBN) shield. Temperature stability is within ± 1°C. Calibration of the F1 was carried out by collecting X-ray data from a single-crystal synthetic periclase at temperatures of 28, 150, 300, 450, 600, 700, 900 and 1000°C, and yielded the equation: a = 0.0000625 (7) [T(K) - 273] + 4.2083 (4), based on the ratio between cell edge and temperature. Structural refinements gave structural parameters and thermal expansion values at the investigated temperature. The mean coefficient of linear expansion up to 1000°C was 14.3 x 10-6 °C.

Keywords

microfurnacehigh-temperaturex-ray diffractionstructure modificationspericlase