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 limit	Maximum 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 accuracy³	Long-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 accuracy³	Long-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 T	14 T	19 T
4.2	11	40	—	—
20	4	—	—	—
40	1.5	12	30	47
66	0.3	2.5	6	9
87	0.2	1.5	4	6
110	0.1	0.9	2.4	—
190	0.03	0.3	0.9	—
300	-0.01	0.1	0.4	—

⁵ Not recommended for use in magnetic fields below 77 K

Temperature response data table (typical)

	RF-100			RF-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	6.892	0.489	0.099	1.5204	0.178	0.16
4.2 K	8.2053	0.418	0.21	1.9577	0.135	0.29
20 K	11.858	0.137	0.23	3.1632	0.0461	0.29
77 K	25.298	0.368	1.1	6.8341	0.0959	1.1
150 K	54.292	0.396	1.1	14.463	0.105	1.1
300 K	111.19	0.373	1.0	29.697	0.101	1.0
400 K	—	—	—	39.824	0.103	1.0

Click here for expanded response table

Physical specifications

	Size	Mass	Lead type	Internal atmosphere	Sensor 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	NA	Rhodium-iron film chip with back side metallized with Mo/Au — if soldered attachment is desired, only indium solder should be used
RF-100-AA	3 mm diam × 8.5 mm long	416 mg	4 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-800-4	3.18 mm × 20.3 mm long	735 mg	4 platinum wire	Solid	Alumina and glass cylindrical case — rhodium-iron alloy wire encapsulated in ceramic

​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.