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​Rhodium-iron sensors have been discontinued. Alternative sensors are Cernox for measuring temperatures from 100 mK to 420 K or Platinum for measuring temperatures from 14 K to 873 K.

Rhodium-Iron Sensor Specifications

Standard curve Not applicable

Recommended excitation Unpackaged chip and RF-100: 0.1 mA; RF-800: 1 mA

Dissipation at recommended excitation 10 µW at 4.2 K, 250 µW at 273 K

Thermal response time Unpackaged chip: 2 ms at 4.2 K, 12 ms at 77 K, 35 ms at 273 K; RF-100: 0.8 s at 4.2 K, 3.6 s at 77 K, 15 s at 273 K; RF-800: 10 s at 273 K

Use in radiation Recommended for use in ionizing radiation environments — Click here for more information

Use in magnetic field Not recommended for use in magnetic fields below 77 K — Click here for more information

Reproducibility1 RF-100: ±10 mK at 4.2 K; RF-800: ±5 mK at 4.2 K

1 Short-term reproducibility data is obtained by subjecting sensor to repeated thermal shocks from 305 K to 4.2 K

Range of use

 Minimum limitMaximum limit
Unpackaged chip 1.4 K 325 K
RF-100-AA 1.4 K 325 K
RF-800-4 0.65 K 500 K2

2 Usable to 800 K, but large and erratic temperature shifts can occur at lower temperature without proper thermal conditioning

Calibrated accuracy: unpackaged chip & RF-100

 Typical sensor accuracy3Long-term stability4
1.4 K ±11 mK ±20 mK
4.2 K±11 mK±20 mK
10 K±12 mK±20 mK
77 K±15 mK±20 mK
305 K±25 mK±20 mK

Calibrated accuracy: RF-800

 Typical sensor accuracy3Long-term stability4
1.4 K ±7 mK ±10 mK
4.2 K±7 mK ±10 mK
10 K±8 mK ±10 mK
77 K±13 mK ±10 mK
305 K ±23 mK ±10 mK
400 K ±41 mK
500 K ±42 mK

3 [(Calibration uncertainty)2 + (reproducibility)2] 0.5 for more information see Appendices B, D, and E
4 Long-term stability data is obtained by subjecting sensor to 200 thermal shocks from 305 K to 77 K

Typical magnetic field-dependent temperature errors5 ΔT/T (%) at B (magnetic induction)

Package parallel to field B
T (K)2.5 T 8 T14 T19 T
4.21140
204
401.5123047
660.32.569
870.21.546
1100.10.92.4
1900.030.30.9
300-0.010.10.4

5 Not recommended for use in magnetic fields below 77 K

Click to Enlarge

Click to Enlarge

Temperature response data table (typical)

 RF-100RF-800-4
 R(Ω)dR/dT
(Ω/K)
(T/R)·
(dR/dT)
R(Ω)dR/dT
(Ω/K)
(T/R)·
(dR/dT)
1.4 K 6.8920.4890.0991.52040.1780.16
4.2 K 8.20530.4180.211.95770.1350.29
20 K 11.8580.1370.233.16320.04610.29
77 K 25.2980.3681.16.83410.09591.1
150 K 54.2920.3961.114.4630.1051.1
300 K 111.190.3731.029.6970.1011.0
400 K 39.8240.1031.0

Click here for expanded response table


Physical specifications

 SizeMassLead typeInternal atmosphereSensor materials
Bare chip
(BR, BG
& BC)
1.3 mm wide ×
3.8 mm long ×
0.38 mm high
7 mg BR: none;
BG: 4 gold;
BC: 4 copper;
— no polarity
NARhodium-iron film chip with back side metallized with Mo/Au — if soldered attachment is desired, only indium solder should be used
RF-100-AA3 mm diam ×
8.5 mm long
416 mg4 phosphor bronze with heavy build polyimide attached with epoxy strain relief at sensor — color coded polarity Helium 4 (4He) standard Rhodium-iron chip is mounted strain-free in a cylindrical gold plated copper can
RF-800-43.18 mm ×
20.3 mm long
735 mg4 platinum wire SolidAlumina and glass cylindrical case — rhodium-iron alloy wire encapsulated in ceramic