Historical research guide · 0843 · 2012
Modified Szpak Protocol for Excess Heat
Dennis Letts · Peter L. Hagelstein
In one minute
Dennis Letts and Peter Hagelstein start from a piece of theory and follow it into the cell. Excess heat in a Fleischmann–Pons experiment, on their reading, needs molecular deuterium sitting inside the palladium, and that can only form where a palladium atom is missing — a vacancy. Vacancies only become favourable once the deuterium-to-palladium ratio reaches about 0.95, which is why the original experiment demands weeks of hard electrochemistry and disappoints so often. Their conclusion is that the classic experiment works partly by accident: palladium and stray impurities plate back onto the cathode at high loading, and that thin outer layer is where the vacancies, and the heat, live. If that is right, the sensible move is to plate on purpose, which is the Szpak co-deposition experiment. That one has been hard to replicate too, and the authors blame low loading, since Szpak’s recipe must run at low current or the palladium will not stick. Their fix is to cut the palladium concentration and raise the current hard.
Connection
Chapter 12 is about getting deuterons close enough together inside a metal lattice for tunnelling to matter, and this paper puts a specific, buildable answer on the table for why that condition is so hard to reach and what to change in the recipe to reach it reliably. It is a chapter 1 sheet as much as a chapter 12 one: a calibrated Seebeck calorimeter checked before every run, an inert titanium cathode as the in-cell null, a matched light-water control, and an endotherm the authors chase down to a chemical reaction rather than leaving it as noise. The Szpak co-deposition method it modifies is on the site at /library/stm-344232fcb0, and Szpak’s own thermal measurements at /library/stm-f6651a4d1a.
From the source
Hydrogen stabilises vacancies in palladium: a monovacancy costs on the order of one electronvolt in pure palladium, but adding hydrogen or deuterium lowers that cost so far that near room temperature and a loading of 0.95 the lattice would find a lower energy by rearranging into a phase with about a quarter of the palladium sites vacant — the superabundant vacancy phase Fukai and Okuma produced as Pd0.75H.Section 2, Vacancies; Figure 1
The mechanism the authors work from is that molecular deuterium cannot form in bulk palladium deuteride because the electron density is too high — about 0.08 electrons per cubic angstrom at the octahedral sites against the roughly 0.033 a sigma-bonded molecule needs — while next to a vacancy it can, which is why loading and loading time are the two requirements the SRI campaign kept running into.Section 2, Vacancies; Section 1 on the SRI thresholds of 0.95 peak loading and 2 to 4 weeks
The classic Fleischmann–Pons cell is read as working through inadvertent co-deposition: elemental analysis finds platinum and other impurities in the outer 100 to 300 nanometres of the cathode, palladium is plating there too, and if that happens at a loading of 0.95 or above then the co-deposited layer carries superabundant vacancies — consistent with helium being found in the gas phase, since helium made deeper than a micron would stay in the lattice.Section 2, closing paragraphs
Their diagnosis of why the Szpak experiment resists replication is the current density: loading rises with current, but Szpak’s 0.05 molar palladium chloride will not adhere at high current, so the protocol is forced to run low and the loading needed to stabilise vacancies is often never reached.Section 3, Codeposition and the Szpak Experiment; Section 11, Discussion
The modified protocol reverses that trade: a copper substrate gold-plated for five minutes, 0.15 molar lithium chloride in 100 grams of 99.9 percent heavy water, and palladium at 0.00125 molar — one fortieth of Szpak’s concentration — co-deposited at about 500 milliamps per square centimetre. Adhesion improved, bridging stopped, and excess power was observed in every experiment run with the protocol.Section 4, Modified Szpak Protocol at High Current Density; Section 11
In experiment 684d the cell held power balance to within 1 percent on the inert titanium cathode, then produced 250 milliwatts of excess power the moment electrolysis was switched to the gold-plated copper cathode, for about 7 kilojoules of excess energy and a 4 to 5 degree rise in cell temperature, with the signal decaying over nine hours once the heavy-water electrolyte was pumped out and replaced with light water; experiment 685 recovered about 110 kilojoules with no sign of diminishing over 60 hours, and the matched pair 690a and 691d gave a 4 kilojoule exotherm in heavy water against a 529 joule endotherm in light water that the authors traced to hypochlorous acid formation with a calculated enthalpy of 503 to 555 joules.Sections 8, 9 and 10; Figures 7, 8 and 9
The way in
https://doi.org/10.70923/001c.72159How to cite it
Dennis Letts, Peter L. Hagelstein (2012) Modified Szpak Protocol for Excess Heat doi:10.70923/001c.72159