Cryostrain: a cryogenic uniaxial strain cell

Cryostrain: a cryogenic uniaxial strain cell

Apply continuously tunable tensile and compressive strains within a cryogenic environment. Suitable for use with scanning probe and confocal microscopy, x-ray and neutron scattering, resistivity, susceptibility and many other measurement techniques. This product is a component for use with a wide range of commercial or home-built cryogenic measurement systems.  

Product Overview

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  • Apply precise, continuously tunable, compressive and tensile strains to samples at cryogenic temperature; without a mechanical feed-through.
  • Highly compact, the entire product range is designed to fit vertically inside a 1" (26 mm) bore (for example a PPMS®) with the smallest size (CS100) being also able to fit horizontally in this tiny space.
  • Temperature compensated – applied strain can be kept constant over a wide temperature range.
  • Operates down to temperatures of below 1 K and in high magnetic field.
  • High strains possible (typically limited only by sample buckling/breaking).
  • Wide angle of access to sample. Suitable for cryogenic scanning probe microscopy

Applications

Match theory to experiment

Significant recent research effort has been spent investigating the electronic and magnetic properties of materials when subjected to uniaxial strains because it allows a convenient way to compare structure/property relationships as predicted from theory experimentally. See Uniaxial Strain in Condensed Matter Physics.

Compatible with a wide range of probes

The cryostrain cell is the ideal component for your cryogenic measurement system -  compatible with a wide variety of different probes, including x-ray diffraction, scanning probe microscopy, optical imaging and electrical measurements.

Complimentary to existing techniques

The cryostrain cells is an ideal companion to diamond anvil cells, providing a complementary technique while also offering better sample access, positive and negative stresses, and in-situ tunability.

A tried and tested technology

The Cryostrain family is based on a technology that has been used in an laboratory environment for more than two years leading to several publications, including a recent high profile paper in the journal science.

Product Specifications

Model NumberCS100CS110CS120CS130
DimensionsLength
Height
Weight
24 mm
13 mm
5g
28 mm
13 mm
5g
32.5 mm
13 mm
5.5g
37 mm
13 mm
5,5g
Maximum sample spring constant15 × 106 N/m5 × 106 N/m3.5× 106 N/m2.6 × 106 N/m
Intended Sample Size2Cross-section
Sample length
0.05 mm2
<1.5 mm
0.04 mm2
<1.5 mm
0.03 mm2
<1.5 mm
0.02 mm2
<1.5 mm
Operating TemperatureLess than 300mK-400K
Maximum applied displacement at zero loadRoom temperature (at -20V/+120V)

Cryogenic temperature ( at ±200 V)
±6 µm (12 µm total range)

±3 µm( 6 µm total range)
±7 µm (15 µm total range)

±4 µm( 8 µm total range)
±13µm (25 µm total range)

±7 µm( 14 µm total range)
±17 µm (34µm total range)

±10 µm( 20 µm total range)
MaterialsChassis
Piezoelectric Stacks
Titanium, unalloyed (Grade 2)
PZT ceramic
ConnectorsDrive
Sensor
4 HV cables3
2 coaxial
Feedback SensorCapacitive - resolution 0.1 nm to 10 nm depending on the capacitance bridge used.

1These maximum values are only for when the cell is used to its maximum room-temperature displacement. For smaller displacements stiffer samples may be used. See the graph below for guidance.

2Sample cross sectional area based on predictions about the spring constant based on typical Young's moduli. Longer samples possible but maximum applied strain will be reduced (strain tuner displacement remains the same).

3Conventional wires can be used up to ~±200 V; contact sales team for more details.

 

Operating Regime

operating regime

 

A summary of the values of acceptable sample spring constants and displacements is shown in the graph to the left.

It follows that large displacements require larger cells, with the CS130 offering the largest displacements. These larger displacements will also cause larger forces within the cell for a given sample spring constant (Hooke’s Law). At a given internal force, the strain cell may be damaged. Thus to remain under this maximum internal force, a larger cell must either apply less than the maximum displacement or samples must be used with smaller spring constants. For smaller displacements, the internal forces never reach this threshold but there is still an upper limit of 5x106 N/M as overly stiff samples will cause an unacceptable amount of twisting in the cell which will affect the accuracy of the position sensor.

Principle of Operation

 

cryostrain_cartoon6_recoloured

To the left shows is an illustration of the CS100 cell. The diagram illustrates the movements in the strain cell when the sample is subjected to positive and negative strains. For demonstration purposes, the movements depicted in the figure have been highly exaggerated.

Thermal Compensation

Piezoelectric stacks lengthen in their polling direction upon cooling. This lengthening is many times longer than the stroke length of the stack, meaning that unless steps are taken, the strain cannot be adequately controlled when the temperature changes. The Cryostrain family of strain cells overcomes this issue with an arrangement of piezoelectric stacks that allows the thermal expansion to cancel out leaving the strain to unaffected by the thermal elongation of the stacks.

Increased Range

Aside from thermal compensation, having pairs of stacks working in opposition to each other means that higher displacements can be generated compared to a single piezoelectric stack glued directly onto the sample; a valuable improvement considering the intrinsically short piezoelectric stroke lengths.

Great access to the strained sample

Mounting the sample on the very top face of the sample maximises the angle of access. For example a scanning probe tip could scan the surface while the sample is mounted on the strain cell.

Customer Requirements

For best results we recommend that customers use the cells with the following equipment;

  • A Razorbill Instruments RP100 power supply is compatible with all four CS1XX strain cell models. This power supply can supply low-noise four quadrant, sink/source voltages of ±200V.
  • Use of the feedback sensor requires the detection of an approximately 1 pF capacitance. For best results, an  Andeen-Hagerling AH2550A Bridge can be used. This bridge can measure capacitances on the order of 1 pF to a precision of 1.4 ppm, corresponding to a displacement sensitivity of less than 1 nm. A much more low cost option that will still offer sub-10nm displacement sensing is the Keysight E4980AL (20 Hz to 300 kHz).

Downloads

CS100 series datasheets

These datasheets contain everything you need to go to get started with one of our products.
They include;

 

An extended list of specifications

Dimensioned drawings of the device

Overview of sample mounting

Approaches to apparatus mounting

A short operation guide

 

To access our download page, please fill in your details into the form below.

CS100 Sample Mounting Guide

Our sample mounting guide is an application note describing a suggested sample mounting procedure. This technical usage note is available on our downloads page which can be accessed after filling in your contact details in the right.

Step by step instructions (with photos) describing the sample mounting procedure.

Advice on epoxy thickness and the use of the supplied sample mounting guides