US 3727052 A
A device for holding and heating a specimen for an X-ray apparatus, for example, an X-ray diffractometer. The device comprises a heater ribbon of an electrical resistance heating material having a flat specimen face. There is a recess cut in the heater ribbon for housing the specimen such that substantial sample temperature uniformity is achieved.
Claims available in
Description (OCR text may contain errors)
tates atent I'mo [ Apr-.10, 1973 SPECIMEN HEATING DEVICE  Inventor: Masaaki Hino,
Akishima-shi, Japan [73 Assignee1, Nihon Denshi Kabushiki Kaisha, Tokyo, Japan Showa-machi,
 Filed: Mar. 10, 1971  Appl. No.1 122,811
52 us. Cl ..250/51.5 [511 Int. Cl. ..GOln 23/20  Field of Search ..250/51.5
 References Cited V UNITED STATES PATENTS 3,148,275 9/1964 Mack ..250/515 3,113,209 12/1963 Shimula ...250/51.5
OTHER PUBLICATIONS I Study of Phase Transitions High-Temperature X-Ray Diffractometer by J. A.
in W0 with a Perr, et al., from the Journal of Applied Physics, Vol. 28, No. 11, Nov. 1957, pages 1272-1275. Adaptation of a Geiger-Counter X-Ray Diffractometer for High-Temperature Investigations by P. Chiotti from The Review of Scientific Instruments, Vol 25, N0. 7, July 1954, pages 683-688.
High Temperature, High Vacuum, Diffractometer Attachment, by J. lntrater et al. from The Review of Scientific Instruments, V01. 32, No. 8, Aug. 1961,
pages 905 & 906.
Primary ExaminerWilliam F. Lindquist Attorney-Webb, Burden, Robinson & Webb ABSTRACT A device for holding and heating a specimen for an X- ray apparatus, for example, an X-ray diffractometer. The device comprises a heater ribbon of an electrical resistance heating material having a flat specimen face. There is arecess cut in the heater ribbon for housing the specimen such that substantial sample temperature uniformity is achieved.
3 Claims, 8 Drawing Figures PAIENTEDAPR 1 01915 3,727, 052
sum 1 UF 3 k W mm PATENTEU 1 0 3, 727, 052
SHEET 2 [IF 3 PATENTEDAPR 1 0 1915 sum 3 0F 3 qv @Pi SPECIMEN HEATING DEVICE The present invention relates to a specimen heating device for use in an X-ray apparatus, especially an X- ray diffractometer. Y
Specimen heating devices of one type or another are frequently used in X-ray diffractometers to enable the analysis of the structure of crystals at elevated temperatures. For example, in the specimen heating device described in US. Pat. No. 3,051,835, the specimen is adjacent to but does not directly touch the heating device and the temperature of the specimen is raised by heat radiation or convection of heat from the heating means. In such a device heat is easily dissipated before being transferred to the specimen. Moreover, the resulting low thermal efficiency makes necessary numerous windings on the heater to maintain the specimen at the required temperature and provides adequate temperature uniformity. This results in high consumption of power.
A device has been proposed in which the specimen is directly mounted on the heater ribbon. Unfortunately, the advantages of such a device outweigh the disadvantages. For example, the specimen is not securely fixed to the heater ribbon and frequently slips off the ribbon surface when tilted during analysis. Further, if the specimen happens to be fairly electrically conductive, it becomes difficult to heat the specimen to a sufficiently high temperature. Still further, the heater is liable to break, since the part of the heater on which the specimen is mounted remains cooler than the surrounding area. Also, the temperature of the specimen is not uniform over the entire area. The edges are somewhat cooler than the center part due to greater thermal radiation at the edges than at the center.
Briefly, according to this invention, a device for heating an X-ray specimen comprises a heater ribbon of an electrical resistance heating material. Exemplary heating materials are platinum rhodium alloys. The ends of the heater ribbon are suitably attached to an adjustable current supply. The ribbon has a flat specimen face with a recess cut into the specimen face for housing the specimen. Preferably, the ratio of the depth of the recess (at its central point) to the thickness of the heater ribbon is between 0.3 and 0.6. It is also preferred that the ratio of the width of the recess to the width of the heater ribbon is between 0.7 and 1. It is clear, of course, that the ratio cannot be precisely 1 or the width of the recess would extend entirely across the ribbon.
It is an advantage of the present invention to provide an improved specimen heating device enabling the specimen to be easily positioned on the heater ribbon. It is an additional advantage of the present invention to provide an improved specimen heating device enabling the specimen to be heated to a high temperature with high efficiency. It is a further advantage of the present invention to provide an improved specimen heating device which maintains substantially uniform specimen temperature of the entire sample.
The invention will be more fully understood by reading the following detailed description in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic diagram of an X-ray diffractometer incorporating a specimen heating device according to this invention;
FIG. 2 is a perspective view of a heating ribbon according to'this invention;
FIG. 3 is a sectional view of the embodiment shown in FIG. 2;
FIGS. 4 A-C show the temperature distribution of the specimen according to the type or design of heater ribbon used; and,
FIGS. 5 and 6 are sectional views of other embodiments of this invention.
Referring to FIG. 1, a radiant energy source, for example, an X-ray tube is disposed on a focusing circle 2. An air-tight casing 3 is centrally mounted on a goniometer 41. Windows 5a and 5b are provided in the casing 3 to allow the X rays produced by the X-ray tube 1 to pass throughv A heating device 6 according to the present invention is also mounted on the goniometer 4. A specimen 7 is placed on the said heating device and heated to the desired temperature directly. The X- radiation from the X-ray tube 1 passes through the window 5a and irradiates the specimen 7. The X-radiation X diffracted by the specimen 7 passes through the window 5b and is detected by adetector 8 which is movably disposed on the focusing circle 2. The output signal from the detector is fed into a recorder (not shown) synchronized with the goniometer 4.
When the incident angle 0 of the irradiating X ray is varied by rotating the goniometer 4, the detector 8 is moved along the focusing circle 2 so as to satisfy the Bragg condition. As a result, the X-ray diffraction profile of the heated specimen is recorded on the recorder.
Referring to FIGS. 2 and 3, the specimen heating device 6 comprises a heater ribbon 9 made of, for example, platinum rhodium alloy.- The bent portions 10a and 10b of said heater ribbon 9 serve to prevent metal deformation due to heat'expansion. A recess 13 cut into the heater ribbon houses the specimen. The recess is cut to satisfy the following conditions enabling uniform temperatures over the entire specimen surface, viz,
0.3 g b/a 0.6 and 0.7 g d/c l where a is the thickness of the heater ribbon, b is the depth of the recess, 6 is the width of the heater ribbon and d is the width of the recess. Electrical terminals 11a and 11b join the ribbon with an adjustable current supply 12.
FIG. 4a shows the temperature distribution over the specimen in accordance with the ribbon used in the prior art having a flat surface. In this case, as apparent from the drawing, the temperature distributions take the form of bell-shaped curves indicating that the temperature distribution over the specimen surface is not uniform.
FIG. 4b shows the temperature distributions when a shallow recess is cut into the heater ribbon 9. In this case, a is 0.4 mm, b is 0.05 mm, c is 14 mm and d is 12 mm. (Accordingly, b/a equals 0.125 and d/c equals 0.857.) A slight improvement in the temperature distribution will be observed but the temperature difference between the edges and center part of the heater is still pronounced.
By increasing the depth of the recess to 0.15 mm as shown in FIG. 4c so that b/a 0.375, optimum temperature distribution uniformity is obtained. An increase in depth beyond 0.15 mm would further improve the uniformity but such considerations are limited by such factors as temperature inequality due to machining errors, possibility of heater ribbon breakage, and the tendency of the center portion of the specimen to increase in temperature as compared with the edges. Accordingly, in this invention, b/a should be maintained below 0.6. At the same time, the lower limit of d/c must not exceed 0.7. If it does, the temperature along the edges of the heater ribbon will not increase sufficiently due to the large heat capacity along said edges.
FIG. 5 is a sectional view showing another embodiment of this invention. In this case, the curved bottom of the recess 13 is convex so that the depth at the edges is greater than that in the center portion. By so doing, the temperature along the edges is higher than that obtained in FIG. 40. FIG. 6 shows a modified version of FIG. 5, in which the polygonal bottom of the recess has flat surfaces which form a convex surface.
Having thus described the invention with the detail and particularity as required by the Patent Laws, what is desired protected by Letters Patent is set forth in the following claims.
l. A holding and heating device for a specimen in an X-Ray apparatus comprising a heater ribbon of an electrical resistance heating material arranged to be heated by passing an electrical current therethrough, said device having at least one substantially flat specimen face, there being a recess in said face, said recess having sidewalls and endwalls extending downward from said flat face to a bottom face, all edges of said bottom face contacting said sidewalls or endwalls, said sidewalls, endwalls and bottom face arranged for direct heat transferring contact with said specimen.
2. A device according to claim 1 wherein the ratio of the depth of the recess to the thickness of the heater ribbon is between about 0.3 and 0.6 and the ratio of the width of the recess to the width of the heater ribbon is between about 0.7 and l.
3. A device according to claim 2 wherein the bottom of the recess has a convex configuration such that the depth of the center of the recess is less than that along the edges.